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排序方式: 共有71条查询结果,搜索用时 15 毫秒
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Chris E. Finlayson Richard H. Friend Matthijs B. J. Otten Erik Schwartz Jeroen J. L. M. Cornelissen Roeland J. M. Nolte Alan E. Rowan Paolo Samorì Vicenzo Palermo Andrea Liscio Kalina Peneva Klaus Müllen Sara Trapani David Beljonne 《Advanced functional materials》2008,18(24):3947-3955
The electronic transport properties of stacks of perylene‐bis(dicarboximide) (PDI) chromophores, covalently fixed to the side arms of rigid, helical polyisocyanopeptides, are studied using thin‐film transistors. In device architectures where the transistor channel lengths are somewhat greater than the average polymer chain length, carrier mobilities of order 10?3 cm2 V?1 s?1 at 350 K are found, which are limited by inter‐chain transport processes. The influence of π–π interactions on the material properties is studied by using PDIs with and without bulky substituents in the bay area. In order to attain a deeper understanding of both the electronic and the electronic‐transport properties of these systems, studies of self‐assembly on surfaces are combined with electronic characterization using Kelvin probe force microscopy, and also a theoretical study of electronic coupling. The use of a rigid polymer backbone as a scaffold to achieve a full control over the position and orientation of functional groups is of general applicability and interest in the design of building blocks for technologically important functional materials, as well as in more fundamental studies of chromophoric interactions. 相似文献
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Child-centered play therapy (CCPT) has been supported as an effective method for working with children. A case study is presented that describes treatment using CCPT with a 7-year-old boy diagnosed with intermittent explosive disorder (IED). This case study delineates 16 sessions of play therapy with a registered play therapist. The behavioral problems the child exhibited at the onset of therapy were greatly improved at the conclusion of the sessions. The outcome of this case study supported the use of play therapy for children with IED. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Earthshine spectra measured by the nadir-viewing Global Ozone Monitoring Experiment (GOME) spectrometer aboard the second European Remote Sensing (ERS-2) Satellite in the range of 240-790 nm are widely used for the retrieval of concentrations and vertical profiles of atmospheric trace gases. For the near-real-time delivery of ozone columns and profiles at the Royal Netherlands Meterological Institute, a tailor-made wavelength calibration method was developed. The method use a high-resolution (0.01-nm) solar spectrum as the reference spectrum and applies both a shift and a squeeze to the wavelengths in selected windows to find the optimal wavelength grid per window. This method provides a calibration accuracy of 0.002 nm below and 0.001 nm above 290 nm. The new wavelength calibration method can be used on any wavelength window, for example, to improve the calibration of spectra from the GOME Data Processor. A software package, GomeCal, which performs this recalibration, along with an improved polarization and radiometric correction, has been made and has been released via the World Wide Web. The method can be used for any high-resolution (ir)radiance spectrometer, such as the satellite instruments SCIAMACHY (Scanning Imaging Absorption Spectrometer for Atmospheric Cartography), Ozone Monitoring Instrument, and GOME-2. 相似文献
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WR Douma A de Gooijer B Rijcken JP Schouten GH Ko?ter ST Weiss DS Postma 《Canadian Metallurgical Quarterly》1997,10(12):2772-2777
Bronchodilator and bronchoconstrictor responsiveness have been considered physiological opposites in patients with obstructive airways disease. Provocation challenges have been replaced by bronchodilator tests in the assessment of cases of severe airways obstruction. The aim of this study was to examine the relationship between bronchoconstrictor and bronchodilator responsiveness, and their supposed interchangeability, in a general population. From the Vlagtwedde-Vlaardingen follow-up study, 101 adults were recruited (mean (SD) age 55 (11) yrs, 67 males and 34 females, and 31 were smokers). All completed a questionnaire on airways symptoms. Bronchoconstrictor and bronchodilator responsiveness were assessed with cumulative dose-response curves, using histamine and terbutaline, respectively. Thus, it was possible to relate histamine sensitivity of the airways (the concentration of histamine, at which forced expiratory volume in one second (FEV1) falls by 10% (PC10)) to the maximal bronchodilator response (delta FEV1) and the sensitivity to the bronchodilator (cumulative dose of inhaled terbutaline at which FEV1 increases by 10% (RD10)). Subjects with a bronchoconstrictor response (PC10 < or = 16 mg x mL(-1); n=38) had more respiratory symptoms than those without (n=63) (40 versus 21%) and also lower baseline FEV1 values (90 versus 96% predicted), but had comparable bronchodilator responsiveness. Subjects with a bronchodilator response (delta FEV1 > or = 9% of the predicted value; n=13) did not differ from those without (n=88) for all parameters, including symptoms, allergy and pulmonary function. In those with a bronchoconstrictor response, there was a weak but significant correlation between the PC10 and RD10 (rho=-0.32), but not between PC10 and delta FEV1. This study suggests that bronchoconstrictor and bronchodilator responsiveness are not highly correlated, even in subjects with airways obstruction. Symptoms were associated with the presence of a bronchoconstrictor, but not a bronchodilator, response. We conclude that bronchoconstrictor and bronchodilator responsiveness are two different phenotypic markers that are not interchangeable in epidemiological studies. 相似文献
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WR Douma HA Kerstjens JM Rooyackers GH Ko?ter DS Postma 《Canadian Metallurgical Quarterly》1998,12(4):848-852
Home peak expiratory flow (PEF) measurements have become the cornerstone of asthma self-management plans. However, the cut-off values for changing treatment have not been formally tested. This study focusses on the possible overtreatment brought about by the different cut-off values and denominators currently employed. Data from 133 clinically stable asthmatic patients from a 2.5 yr follow-up study were analysed. The results showed that strict adherence to current criteria would lead to severe overtreatment, with up to 30% of clinically stable patients crossing into the lowest (red) zone at least once a year when personal best is the denominator and when it has not been limited to a defined time of day or to defined prior bronchodilator use. As expected, the passage of clinically stable patients into the lower zones became less frequent when cut-off values were sharpened and when time- and treatment-specific PEFs were used as the denominators. Strict adherence to commonly used peak expiratory flow cut-off values would lead to considerable overtreatment. In order to avoid overtreatment, the morning peak expiratory flow before any (bronchodilator) treatment should be related to the personal best peak expiratory flow measured under the same conditions. The choice of the right cut-off value will also depend on studies being performed to test the amount of undertreatment with a given value. 相似文献